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Commit 8746515d authored by Stefano Stabellini's avatar Stefano Stabellini Committed by David Vrabel
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xen: Add __GFP_DMA flag when xen_swiotlb_init gets free pages on ARM 



Make sure that xen_swiotlb_init allocates buffers that are DMA capable
when at least one memblock is available below 4G. Otherwise we assume
that all devices on the SoC can cope with >4G addresses. We do this on
ARM and ARM64, where dom0 is mapped 1:1, so pfn == mfn in this case.

No functional changes on x86.

From: Chen Baozi <baozich@gmail.com>

Signed-off-by: default avatarChen Baozi <baozich@gmail.com>
Signed-off-by: default avatarStefano Stabellini <stefano.stabellini@eu.citrix.com>
Tested-by: default avatarChen Baozi <baozich@gmail.com>
Acked-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: default avatarDavid Vrabel <david.vrabel@citrix.com>
parent a71dbdaa

arch/arm/include/asm/xen/page.h

+1 −0
Original line number Diff line number Diff line
@@ -110,5 +110,6 @@ static inline bool set_phys_to_machine(unsigned long pfn, unsigned long mfn) 
bool xen_arch_need_swiotlb(struct device *dev,

			   unsigned long pfn,

			   unsigned long mfn);

unsigned long xen_get_swiotlb_free_pages(unsigned int order);



#endif /* _ASM_ARM_XEN_PAGE_H */

arch/arm/xen/mm.c

+15 −0
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 
#include <linux/gfp.h>

#include <linux/highmem.h>

#include <linux/export.h>

#include <linux/memblock.h>

#include <linux/of_address.h>

#include <linux/slab.h>

#include <linux/types.h>
@@ -21,6 +22,20 @@ 
#include <asm/xen/hypercall.h>

#include <asm/xen/interface.h>



unsigned long xen_get_swiotlb_free_pages(unsigned int order)

{

	struct memblock_region *reg;

	gfp_t flags = __GFP_NOWARN;



	for_each_memblock(memory, reg) {

		if (reg->base < (phys_addr_t)0xffffffff) {

			flags |= __GFP_DMA;

			break;

		}

	}

	return __get_free_pages(flags, order);

}



enum dma_cache_op {

       DMA_UNMAP,

       DMA_MAP,

arch/x86/include/asm/xen/page.h

+5 −0
Original line number Diff line number Diff line
@@ -269,4 +269,9 @@ static inline bool xen_arch_need_swiotlb(struct device *dev, 
	return false;

}



static inline unsigned long xen_get_swiotlb_free_pages(unsigned int order)

{

	return __get_free_pages(__GFP_NOWARN, order);

}



#endif /* _ASM_X86_XEN_PAGE_H */

drivers/xen/swiotlb-xen.c

+1 −1
Original line number Diff line number Diff line
@@ -235,7 +235,7 @@ int __ref xen_swiotlb_init(int verbose, bool early) 
#define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT))

#define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT)

		while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {

			xen_io_tlb_start = (void *)__get_free_pages(__GFP_NOWARN, order);

			xen_io_tlb_start = (void *)xen_get_swiotlb_free_pages(order);

			if (xen_io_tlb_start)

				break;

			order--;